Synthetic resins and process of making same



Patented Aug. 23, 1938 UNITED STATES SYNTHETIC RESINS AND PROCESS OFMAK- ING SAME Theodor Sutter, Basel,

Switzerland, assignor to Ciba Products Corporation, Dover, DeL, acorporation N0 Drawing. Original application June 30, 1931,

Serial No. 548,039.

Divided and this application January 24, 1936,- Serial No. 60,737.

Switzerland July 11, 1930 6 Claims.

This application is a division of my application for patent Serial No.548,039 filed in the U. S. on June 30, 1931, and in Switzerland on July11, 1930.

This invention relates to synthetic resins from primary aromatic aminesand aldehydes. It comprises the process for the manufacture of theseresins, the new products themselves, as well as the application of samein the industry of synthetic resins. I

It is known that by treating aromatic amines in presence of about theequivalent proportion of a mineral acid with formaldehyde or a substanceyielding formaldehyde and subsequently separating the acid, both solubleand fusible and insoluble and infusible condensation products can beobtained accordingly as a smaller or larger proportion of aldehyde isbrought into reaction.

Particularly, valuable are the resins obtained from aniline andformaldehyde which are characterized by a surprising mechanical,electrical and chemical resistance.

Further, in British Patent Nos. 342,325 and 342,723, there is describedthat the soluble and fusible resins obtained with at most one molecularproportion of formaldehyde can be converted by treatment with analdehyde or a substance yielding aldehyde into infusible resins ofessentially improved properties.

The present invention is based on the observation that this reaction isin no way limited to the condensation products with at most onemolecular proportion of formaldehyde, it having been found that theproducts with essentially more than one molecular proportion offormaldehyde are profoundly changed in their properties or improved bytreatment with further quantities of aldehyde or substance yieldingaldehyde. In particular both the tendency of the resin to flow andthe'strength or resistance to distortion at raised temperature and thechemical resistance of the finished products may be very stronglyinfluenced, since, it being possible to use gradually or rapidlycondensing aldehydes, or mixtures of aldehydes, there is at hand anextraordinarily wide range of the speed of hardening and stability ofthe new resins. It'

appears, therefore, that the characteristic properties of theformaldehyde-amine-resins are maintained even when relatively very largeadditions of other aldehydes and substances yield- When one starts withing aldehyde are made. vcondensation products capable "of being pressedat high temperature, it is preferable to use high' molecular aldehydes,which react gradually, or substances which liberate their aldehyde onlyat a high temperature, for instance the phenol-polyalcohols, theseserving in the first phase as a flux and thus facilitating the pressingoperation at a relatively low temperature and then reacting withformation of bodies which are very resistant to heat and chemicalinfluence. However, there can also be added from the first a flux in thesense of British Patent No. 342,730. As aldehydes suitable for theinvention may be named para-formaldehyde, furfural, crotonic aldehyde,paraldehyde, benzaldehyde, salicylaldehyde, toluenesulfosalicylaldehyde,oenanthic aldehyde or the like. As substances yielding aldehyde suitablefor the invention may be named furfuramide, hexamethylenetetramine,phenolpolyalcohols or the like. The last-named are particularlysuitable, because on the one hand they enter into reaction very slowlyand on the other hand harden then quickly to'a finished product.Combinations of amine resins con taining not much more than onemolecular proportion of formaldehyde with gradually reacting agents,such as furfural or phenol-polyalcohols or mixtures of these, flow soeasily and have such a high stability at moderate temperatures that theycan be hardened in molds without pressure and fill even complicatedmolds without leaving empty spaces. 1

The speed of the hardening may be still further influenced by theaddition of basic substances, such as furfuramide, triethanolamine orthe like or by acids.

The components may be mixed at any stage of the production. Aparticularly favorable condition is created by the fact that theamine-formaldehyde-resin, when the acid is separatedprecipitates in aform having such alarge surface and high absorptive capacity that veryconsiderable quantities of aldehyde soluble in water or substancesyielding aldehyde are firmly retained, so that in the washing operationno considerable losses occur. In this manner a particularly uniformdispersion can be obtained. If desired, the aldehyde orphenol-polyalcohol may be introduced into the acid condensation solutionand then the acid eliminated, or after the elimination of the acid theseparated amine-formaldehyde-resin may be worked up with the hardeningagent or, finally, the dry components may be united by mixing, grinding,melting together or like operation, the aldehyde, if desired, beingdiluted with a. solvent for the purpose of uniform distribution. At anystage of the operation, it

til

desired even at the first condensation, there may be added a fiuxingagent, a filler or another addition, such as has been already proposedin British Patent Nos. 342,325, 342,723, 342,326, and 342,730. Themixing of the components'in solution or suspension is particularlyuseful for homogeneous fixation of the resin on or in substrata, such aspaper pulp, wood-meal, asbestos, paper or textile fabrics, whichfixation can be conducted as described for amine-formaldehyderesins inBritish Patent Nos. 284,589, 342,325, 342,723, and 342,326. The newproducts are applicable for very various purposes in the industry ofartificial materials, for instance for insulating materials, for makinguseful and artistic objects of all kinds, as constructional material formachine parts or the like which must withstand a comparatively strongstrain, for instance toothed guide wheels, parts of textile machines,such as spools or shuttles; also as material for packing Joints,substitutes for wood in the furniture and building industries; finallyfor gramophone records, loud speakers and other appliances for theacoustic industry.

The following examples illustrate the invention, the parts being byweight Emmple 1 93 parts of aniline (1 mol.) are mixed with 120 parts ofhydrochloric acid of 36 per cent. strength (1.2 mols) and 930 parts ofwater. There are then added 105 parts of formaldehyde of 40 per cent.strength (1.4 mols). The mixture, as soon as it has become orange tored, is stirred into 2000 parts of caustic soda solution of 5 per cent.strength.

There is precipitated a white to feebly reddish,

voluminous powder which is washed and dried.

100 parts of the infusible resin thus obtained are ground with 10 partsof para-cresoldimethylol and 10 parts of furfural and the mixture ispressed. There are obtained homogeneous forms of excellent properties.

Example 2 100 parts of an infusible resin, made as described in Example1, are thoroughiy groundwith 15 parts of para-cresoldimethylol and 1part of salicylic acid and the mixture is pressed at 160 C. The powder,which flows well in the first stage of the pressing, hardens veryquickly to a form which is very stable to heat.

Example 3 93 parts of aniline are dissolved in the equivalent quantityof dilute hydrochloric acid and the solution is stirred with 95 parts ofa formaldehyde solution of 38 per cent. strength for some time at 50 C.This solution is now poured into a mixture of phenol-polyalcohols, suchas is obtained by allowing to stand for several days in the cold adilute alkaline solution of 15 parts of phenol containing 2% equivalentsof formaldehyde. The neutralization is completed with sodium carbohatesolution and the whole is heated, if necessary to C., and filtered, andthe solid matter is washed and dried. The powder thus obtained flowswell and yields under pressure forms of very good stability to heat andresistance to fracture. Instead of phenol as the parent material for theflenol-poiyalcohols homologues of phenol or mixtures of these,para-dihydroxydiphenylpropane or thelikemaybeused'inwhichcaseitmaybeadvantageous to use more 2 mols formaldehyde for each phenol-hydroxyl.

Example 4 Into an acid condensation solution prepared from 93 parts ofaniline, 600 parts of hydrochloric acid of 7 per cent. strength and 83parts of 8. formaldehyde solution of 38 per cent. strength, there is runan alkaline solution of 20 parts of phenoi-polyalcohol prepared asdescribed in Example 3, and the whole is stirred for some time with 120parts of wood meal. The greater part of the acid is then neutralizedwith caustic soda solution and the neutralization finished with sodiumcarbonate, whereafter filtration, washing and drying follow. The finelyground powder can be pressed to filled forms of excellent properties.

- Example 5 pzrts of anhydroformaldehydeaniline are suspended in 400parts of water and the suspension is mixed with a solution of parts ofhydrochloric acid of 37 per cent. strength in 300 There are added 10parts of formaldehyde and the whole is stirred at 60-90 C. until a clearsolution is produced and there is added a solution ofphenol-polyalcohols, prepared as described in Example 3 from 20 parts ofphenol, and the condensate is poured, while stirring well, into a magmaof paper pulp containing 120 parts of dry cellulose. After some stirringneutralization, filtration and washing follow. The matter retained bythe filter can be worked up in a beater and made into paper in the usualmanner. By superimposing and pressing these sheets of paper bodies ofextraordinary mechanical and electrical resistance can be produced.

The term primary aromatic amine, as employed in this application, isintended to cover not only true primary aromatic amines, such as anilineand its homologues, but also such deriva-v tives thereof which under theconditions of the condensation described herein, also act like the trueprimary aromatic amines under the conditions of the present process toyield the same resins, for example, anhydroformaldehydeaniline,formylaniline or the homologues of these compounds, and the like.

i The expression .formaldehyde yielding compounds" as employed herein,is intended to cover not only formaldehyde itself, but its polymers orany other substances splitting oi! formaldehyde or capable of formingmethylene -links under the conditions of the condensation, as it hasbeen found that such substances or polymers may also be used in place offormaldehyde itself.

The term synthetic resinous material, as used in this specification andclaims, is intended to cover not only the pure resin, but all forms inwhich such resin may occur, namely, resin solutions,'molding powder,molded article, impregnated cellulose material, in sheet form or loose,with or without the addition of fillers, plastifiers, coloringmaterials, and the like.

By the term phenol-polyalcohols" there is meant, generically, theproducts resulting from the reaction of more than one molecularproportion of formaldehyde on one molecular proportion of a phenol, suchas phenol-polymethylol, cresoldimethylol, in presence of cold aqueousalkali;

than an equimolecular proportion of a formalde- 75 hyde yieldingcompound in the presence of a mineral acid and subsequentlyprecipitating the prodnot by an agent of alkaline character, whichcomprises adding phenolpolyalcohols to said amineformaldehydecondensation product in any phase of its production.

2. Process for improving both the flux and the resistance to distortionunder heat of anilineformaldehyde condensation products obtained byreacting aniline with more than an equimolecular proportion of aformaldehyde yielding compound in the presence of a mineral acid andsubsequently precipitating the product by an agent ofalkaline character,which comprises adding phenolpolyalcohols to said aniline-formaldehydecondensation product in any phase of its production.

3. Process for improving both the flux and the resistance to distortionunder heat of anilineformaldehyde condensation products obtained byreacting aniline with more than an equimolecular proportion of aformaldehyde yielding compound in the presence of a mineral acid andsubsequently precipitating the product by an agent of alkalinecharacter, which comprises adding cresol-dimethyloi to saidaniline-formaldehyde,condensation product in any'phase of itsproduction.

4. A synthetic resinous material of good flux and capable of formingmolded bodies of high resistance to distortion under heat, comprisingessentially a condensation product, obtained by reacting a primaryaromatic amine with more than an equimolecular proportion of aformaldehyde yielding compound in the presence of a mineral acid andsubsequently precipitating the product by an agent of alkalinecharacter, combined with phenolpolyalcohols.

5. A synthetic resinous material of good flux and capable of formingmolded bodies of high resistance to distortion under heat, comprisingessentially a condensation product, obtained by reacting aniline withmore than an equimolecular proportion of a formaldehyde yieldingcompound in the presence of a mineral acid and subsequentlyprecipitating the product by an agent of alkaline character, combinedwith phenolpolyalcohols.

6. A' synthetic resinous material of good flux and capable of formingmolded bodies of high resistance to distortion under heat, comprisingessentially a condensation product, obtained by reacting aniline withmore than an equimolecular proportion of a formaldehyde yieldingcompound in the presence of a mineral acid and subsequentlyprecipitating the product by an agent of alkaline character, combinedwith cresol-dimethylol.

v'r'nnonon SUTTER.

